Wednesday, September 26, 2007

Flashback : Hong Kong, 1998 & Professor Shortridge

We're going to be writing about microbiologist Professor Kennedy Shortridge in the next week, so we thought as way of an introduction, we'd go back to the Hong Kong outbreak of H5N1, where the reality of a coming human bird flu pandemic first grabbed world headlines and brought Professor Shortridge to international prominence for his fight against the spread of the virus.

From the British Medical Journal :

The outbreak of avian flu in Hong Kong continues to ring alarm bells and dominate headlines worldwide. The H5N1 influenza A virus has been confirmed in 16 people and is suspected in another four cases. Four people have died, and three remain in a critical condition.

Because these are the world's first reported human cases of a flu strain previously known to infect only birds, fears have been raised that the virus might spark a flu pandemic. There are too many unanswered questions, however, for anyone to be sure. For example, researchers have yet to determine the original source of the virus, the mode of transmission from birds to humans, whether human to human transmission is possible, what the incidence is in Hong Kong, whether fowl or animals apart from chickens are affected, whether anyone in mainland China has been infected with the disease, and the rate at which the virus is mutating.

The outbreak began in early May, when a 3 year old boy died from respiratory failure secondary to viral pneumonia. When scientists at Hong Kong's Department of Health could not identify the strain they sent specimens to centres in Britain, the United States, and the Netherlands. By August all had identified the strain as H5N1, a typically avian virus. The second case was not confirmed until November. According to Professor Kennedy Shortridge, a microbiologist at the University of Hong Kong, the H5N1 strain was first isolated by the Department of Agriculture and Fisheries in Hong Kong after an outbreak in 6800 chickens on three farms between late March and early May last year. "The overall mortality rate exceeded 70%, and on two farms the mortality rate came close to 100%," he said.

Researchers at the University of Hong Kong are working with the World Health Organisation to identify the reservoir of the H5N1 virus in poultry and animals by testing domestic and wild birds, as well as dogs, cats, rats, and any other animals that have close contact with humans, for the presence of the H5N1 virus.

Professor Shortridge said that rigorous follow up is essential, and few animals can be ruled out at this stage: "The virus has cropped up under different circumstances, and so little is known about it. If the virus is shed through faeces, as has been suggested, then in theory there could be a lot of virus in the environment. Humans can be infected–perhaps other animals can be infected as well. At the moment we don't know."

Until now it had been thought that new strains of human flu (variations of H1, H2, or H3) emerge after the virus's genes have been reassorted in pig cells with genes from strains of human or avian flu, or both. Pigs are considered a mixing vessel because they have avian, human, and swine flu receptors. But the H5N1 virus, a purely avian strain, has leapt directly from bird to humans.

According to Ms Reynolds, this is significant because it is a new disease in humans, who have no resistance to the virus. "If it becomes efficient in transmitting from human to human then the entire world is vulnerable, and there is the potential for a pandemic." However, she added: "There is no way to predict whether or not this will happen. The virus could go away, it could mutate and become more potent, or it could mutate and become more benign."

Some excerpts from a remarkable speech Professor Shortridge gave in December 2004 (excerpts) :
It was in microbiology classes that the germ of an idea began to smoulder.

That germ had its genesis when, as a little boy, my mother told me how, in our country town, in the great influenza pandemic of 1918-19, a man on a horse-and-cart would call from the street for the bodies of those who had died from influenza. Her story was compelling, her concern was compelling.

During this pandemic, some 20 to 40 million died worldwide. The major concern was that a virus with the same potential for human devastation could arise again.

Comprehending death rates of 1/100 to 1/50 almost beggars belief. They need to be viewed against the nutritional deficits and social dislocation of the time.

Her story and such figures had a tremendous impact upon me. While in London in the late 1960s, fortuitous findings on animals, some originally from Hong Kong, led me to suspect a possible connection between animals and influenza pandemics. The seeds were sown – leading me to The University of Hong Kong in 1972 to explore this, with the ideal of getting ahead of the next pandemic.

This led me into the field of influenza ecology. At that time, and for many years, it was regarded by many as an academic curiosity – but it was an interesting exercise worth pursuing nevertheless.

As the years rolled by, there was increasing evidence of interspecies transmission of influenza viruses noted by Hong Kong and other groups. Circumstantial evidence for the role of avian influenza viruses in the origin of human influenza pandemics was increasing.

...the world has many problems in spite of the great advances in science and technology.

We should be moving into a higher order of human development but we are not.

This does not make any sense – it is almost as if human development, rather than going forward, is in some ways, going backwards. Loneliness abounds, we could treat our fellow human beings better, we could treat our wonderful animals better, we should treat this fragile planet better.

Somewhere in this equation, this unsatisfactory situation, the world is being subjected to the added pressures of emerging and re-emerging infectious diseases. In the past 50 years or so, infectious, zoonotic viral diseases have left their mark on the world, for example, HIV/AIDS, haemorrhagic fevers such as Ebola, West Nile, influenza H5N1 “bird flu”, SARS. Other avian influenza viruses are waiting in the wings.

The world is under serious threat from infectious diseases. It is as if Nature holds all the aces, but really we should be in partnership with Nature.

In the current influenza situation, the potential threat to the global community is great – to humans, to poultry and to bird life. While such a situation apparently did not exist prior to 1997, a global catastrophe extending beyond humans is within the realm of the possible. All the more so, since poultry is now the major meat protein worldwide.

I am increasingly convinced that if we are ever going to deal with zoonotic diseases at source, we will need to have a better relationship with animals – all animals – an intrinsically important step in itself toward improving human development. A sobering thought here is that pandemic influenza is now regarded as a non-eradicable zoonotic disease.

A higher aspiration in human development is that we might look forward to the time when ALL disease is eliminated. This will mean upping the stakes to take in all of Nature. As I have said in one of my publications "Only when we are at peace with Nature, will disease begin to melt away".

Sure, this is a pious hope – I believe bringing infectious diseases to heel is within the realm of the possible and we must start somewhere.

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